Mitigating Nitrogen Losses: The Role of Enhanced Efficiency Fertilizers in Sustainable Corn Production

Authors

Dipesh Giri, University of Nebraska-LincolnFollow

First Advisor

Javed Iqbal

Committee Members

Bijesh Maharjan, Joe Luck

Date of this Version

5-2025

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the Degree of Master of Science

Major: Agronomy

Under the supervision of Professor Javed Iqbal

Lincoln, Nebraska, May 2025

Comments

Copyright 2025, Dipesh Giri. Used by permission

Abstract

Nitrogen (N) is essential for crop production, but its inefficient use often leads to environmental losses through nitrate leaching, ammonia volatilization, and nitrous oxide (N₂O) emissions. Enhanced efficiency fertilizers (EEFs), such as nitrification inhibitors (NIs) and urease inhibitors (UIs), have been developed to minimize these losses and improve nitrogen use efficiency (NUE). This research combined a multi-year field experiment and a controlled laboratory study to evaluate how dual-inhibitor fertilizers compare to conventional urea and single-inhibitor formulations in Nebraska cropping systems. The main objective was to understand how nitrogen inhibitors influence N availability, crop performance, and nitrogen losses across different environmental conditions and soil types. The three-year field study, conducted at the Eastern Nebraska Research, Extension, and Education Center (ENREEC), showed that the dual-inhibitor fertilizer (Trident, which contains both a urease and a nitrification inhibitor) improved soil ammonium retention, moderated nitrate fluctuations, and increased corn yield—especially in wetter conditions. In 2024, which had a wet early growing season, the dual-inhibitor treatment increased ammonium concentration by 47% and corn yield by 9% compared to standard urea. However, in 2022 and 2023—both drier years—no major differences in N availability or yield were observed between treatments, highlighting the importance of adequate moisture for the dual inhibitor’s effectiveness. The lab study further explored how single and dual inhibitors perform under controlled conditions. Nitrification inhibitors reduced nitrate leaching by 10–16% more than dual inhibitors, especially in coarse-textured soils. On the other hand, dual inhibitors reduced ammonia volatilization more effectively—by 68–75% compared to single inhibitors. There were no clear differences in N₂O emissions between treatments, suggesting similar behavior for this pathway across products. Overall, these findings point to the importance of context-specific nitrogen management. In sandy soils prone to leaching, nitrification inhibitors may offer better control over nitrate loss. In contrast, in fine-textured or irrigated systems with higher volatilization risk, dual inhibitors can be a more suitable option, provided that moisture is not limiting. These results suggest that there is no one-size-fits-all solution, and nitrogen management should be tailored to local soil and weather conditions to balance productivity and environmental goals.

Advisor: Javed Iqbal